1 /* 2 * Housekeeping management. Manage the targets for routine code that can run on 3 * any CPU: unbound workqueues, timers, kthreads and any offloadable work. 4 * 5 * Copyright (C) 2017 Red Hat, Inc., Frederic Weisbecker 6 * Copyright (C) 2017-2018 SUSE, Frederic Weisbecker 7 * 8 */ 9 #include "sched.h" 10 11 DEFINE_STATIC_KEY_FALSE(housekeeping_overriden); 12 EXPORT_SYMBOL_GPL(housekeeping_overriden); 13 static cpumask_var_t housekeeping_mask; 14 static unsigned int housekeeping_flags; 15 16 int housekeeping_any_cpu(enum hk_flags flags) 17 { 18 if (static_branch_unlikely(&housekeeping_overriden)) 19 if (housekeeping_flags & flags) 20 return cpumask_any_and(housekeeping_mask, cpu_online_mask); 21 return smp_processor_id(); 22 } 23 EXPORT_SYMBOL_GPL(housekeeping_any_cpu); 24 25 const struct cpumask *housekeeping_cpumask(enum hk_flags flags) 26 { 27 if (static_branch_unlikely(&housekeeping_overriden)) 28 if (housekeeping_flags & flags) 29 return housekeeping_mask; 30 return cpu_possible_mask; 31 } 32 EXPORT_SYMBOL_GPL(housekeeping_cpumask); 33 34 void housekeeping_affine(struct task_struct *t, enum hk_flags flags) 35 { 36 if (static_branch_unlikely(&housekeeping_overriden)) 37 if (housekeeping_flags & flags) 38 set_cpus_allowed_ptr(t, housekeeping_mask); 39 } 40 EXPORT_SYMBOL_GPL(housekeeping_affine); 41 42 bool housekeeping_test_cpu(int cpu, enum hk_flags flags) 43 { 44 if (static_branch_unlikely(&housekeeping_overriden)) 45 if (housekeeping_flags & flags) 46 return cpumask_test_cpu(cpu, housekeeping_mask); 47 return true; 48 } 49 EXPORT_SYMBOL_GPL(housekeeping_test_cpu); 50 51 void __init housekeeping_init(void) 52 { 53 if (!housekeeping_flags) 54 return; 55 56 static_branch_enable(&housekeeping_overriden); 57 58 if (housekeeping_flags & HK_FLAG_TICK) 59 sched_tick_offload_init(); 60 61 /* We need at least one CPU to handle housekeeping work */ 62 WARN_ON_ONCE(cpumask_empty(housekeeping_mask)); 63 } 64 65 static int __init housekeeping_setup(char *str, enum hk_flags flags) 66 { 67 cpumask_var_t non_housekeeping_mask; 68 int err; 69 70 alloc_bootmem_cpumask_var(&non_housekeeping_mask); 71 err = cpulist_parse(str, non_housekeeping_mask); 72 if (err < 0 || cpumask_last(non_housekeeping_mask) >= nr_cpu_ids) { 73 pr_warn("Housekeeping: nohz_full= or isolcpus= incorrect CPU range\n"); 74 free_bootmem_cpumask_var(non_housekeeping_mask); 75 return 0; 76 } 77 78 if (!housekeeping_flags) { 79 alloc_bootmem_cpumask_var(&housekeeping_mask); 80 cpumask_andnot(housekeeping_mask, 81 cpu_possible_mask, non_housekeeping_mask); 82 if (cpumask_empty(housekeeping_mask)) 83 cpumask_set_cpu(smp_processor_id(), housekeeping_mask); 84 } else { 85 cpumask_var_t tmp; 86 87 alloc_bootmem_cpumask_var(&tmp); 88 cpumask_andnot(tmp, cpu_possible_mask, non_housekeeping_mask); 89 if (!cpumask_equal(tmp, housekeeping_mask)) { 90 pr_warn("Housekeeping: nohz_full= must match isolcpus=\n"); 91 free_bootmem_cpumask_var(tmp); 92 free_bootmem_cpumask_var(non_housekeeping_mask); 93 return 0; 94 } 95 free_bootmem_cpumask_var(tmp); 96 } 97 98 if ((flags & HK_FLAG_TICK) && !(housekeeping_flags & HK_FLAG_TICK)) { 99 if (IS_ENABLED(CONFIG_NO_HZ_FULL)) { 100 tick_nohz_full_setup(non_housekeeping_mask); 101 } else { 102 pr_warn("Housekeeping: nohz unsupported." 103 " Build with CONFIG_NO_HZ_FULL\n"); 104 free_bootmem_cpumask_var(non_housekeeping_mask); 105 return 0; 106 } 107 } 108 109 housekeeping_flags |= flags; 110 111 free_bootmem_cpumask_var(non_housekeeping_mask); 112 113 return 1; 114 } 115 116 static int __init housekeeping_nohz_full_setup(char *str) 117 { 118 unsigned int flags; 119 120 flags = HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | HK_FLAG_RCU | HK_FLAG_MISC; 121 122 return housekeeping_setup(str, flags); 123 } 124 __setup("nohz_full=", housekeeping_nohz_full_setup); 125 126 static int __init housekeeping_isolcpus_setup(char *str) 127 { 128 unsigned int flags = 0; 129 130 while (isalpha(*str)) { 131 if (!strncmp(str, "nohz,", 5)) { 132 str += 5; 133 flags |= HK_FLAG_TICK; 134 continue; 135 } 136 137 if (!strncmp(str, "domain,", 7)) { 138 str += 7; 139 flags |= HK_FLAG_DOMAIN; 140 continue; 141 } 142 143 pr_warn("isolcpus: Error, unknown flag\n"); 144 return 0; 145 } 146 147 /* Default behaviour for isolcpus without flags */ 148 if (!flags) 149 flags |= HK_FLAG_DOMAIN; 150 151 return housekeeping_setup(str, flags); 152 } 153 __setup("isolcpus=", housekeeping_isolcpus_setup); 154